In 1981, Electronics awarded Carver Mead and Lynn Conway
the magazine's annual Award for Achievement. Electronics was very
widely read and highly regarded in the industry at the time. This
award article sketches the story of the Mead-Conway work, and
indicates the major impact their work was having within just 2
years of emerging from Xerox PARC and Caltech. The article follows:

by Martin Marshall, Larry Waller, and Howard
Wolff of the Electronics staff

The impact of Carver Mead and Lynn Conway on the design of
very large-scale integrated circuits is bringing about a fundamental
reassessment of how ICs are put together. Mead, the Caltech professor,
and Conway, the Xerox system designer, have optimized the VLSI
process by melding the concepts of fabrication at the device level
and architecture at the system level to produce truly integrated
systems.

The work they have done, individually and together, brought
to fruition in their seminal textbook, "Introduction to VLSI
Systems," is truly monumental. In the area of structured
IC-design methodology, they not only have helped spawn a common
design culture so necessary in the VLSI era, but they have greatly
increased interaction between university and industry so as to
stimulate research by both.

Putting their methodology between the covers of a book, one
that is now used by more than 100 universities around the world,
was only part of their accomplishment-even if it did take the
better part of two years. Rather, gaining acceptance for some
of the book's underlying assumptions is at the heart of the matter.

Some theorists who create an important body of work stop there,
leaving the task of popularizing it to others. Mead and Conway
regarded their theories as only the beginning and set out to popularize
them. The vehicle was the classroom: Mead through his graduate
classes in Pasadena at the California Institute of Technology,
and Conway through a landmark course she taught in 1978-79 at
the Massachusetts Institute of Technology in Cambridge as visiting
professor in electrical engineering and computer science.

Mead, who describes himself as a "lifer" at Caltech,
did his undergraduate and graduate work there and then served
as assistant professor and associate professor before obtaining
the Gordon and Betty E. Moore professorship, a chair endowed by
and named after the chairman of Intel Corp. and his wife. Conway
is transplanted from New York, with bachelor's and master's degrees
from Columbia University's School of Engineering and Applied Science.

For Mead, the seeming rush toward acceptance of his once controversial
ideas on simplified custom-circuit design has been anything but
sudden. He has promoted his ideas whenever and wherever possible
over the past decade, facing dismissal by most of a skeptical
semiconductor industry. What support he did gain came mostly from
computer and systems firms interested in affordable high- performance
devices tailored to their needs. But giant semiconductor houses
were implacable in ignoring him and his version of design automation
- what used to be called computer-aided design. There was one
notable exception: Intel Corp., the Santa Clara, Calif., semiconductor
maker, with which Mead has long had close ties.

About two years ago industry opinion began to shift toward
Mead's views. The major impetus was provided by the book, which
even before its official 1979 publication date had already established
itself at such top schools as MIT, the University of California
at Berkeley, and Carnegie-Mellon University in Pittsburgh. Mead
recalls, "It was Lynn's idea to copy the first chapters to
enable the schools to start their VLSI courses. She is particularly
good at propagating knowledge."

For all its impact, the basic concept formulated by Mead and
Conway is simple. It holds that ICs are so complex and dense that
human designers cannot deal with individual devices; instead,
they must be handled at a higher level of integrated system architecture.
Though today this is a truism because of VLSI's complexity, that
view was radical when it was first enunciated some 10 years ago.

Still, the implications of the Mead-Conway concept disturbed
semiconductor industry powers. For one thing, it advocates establishing
many small groups to design custom proprietary circuits, attacking
the concept of the standard IC, which was the bread and butter
of the business. For another, in the mid- I 970s Mead in particular
began calling for what are called silicon foundries that would
accept and fabricate independent designs. (The term silicon foundry
was coined by Intel's Moore, but Mead disseminated it.) it

The unpopularity of such views was almost inevitable. One well-aimed
criticism called the approach an oversimplification of the difficulties
of device design and held that it overburdened fabrication engineers.
Another barb claimed the approach failed to account for basic
differences among process technologies.

Another source of friction was Mead's prediction of a widespread
restructuring of the semiconductor business to separate design
and fabrication functions. It is not surprising that industry
officials who struggled to build their companies grumbled about
"ivory tower academics" who offered economic advice.

Such criticism is brushed aside by Mead. He simply points to
events of the past year, which he believes are proving out his
ideas and moving the industry in the directions he charted-for
example, Intel's establishment of a silicon foundry in Chandler,
Ariz. [Electronics, Sept. 8, p. 39]. Smaller firms have been springing
up. Mead is quick to predict that the spread of the Mead-Conway
design-automation concepts signals nothing less than "an
innovative revolution that, once started, nothing will stop."

Mead and Conway's collaboration dates back to 1975, when Conway
began to participate on behalf of Xerox in what became the Silicon
Structures Project. Her participation was the result of the cooperative
effort between Xerox and Caltech put together by the brothers
Bert and Ivan Sutherland. Bert was manager of the systems science
laboratory at Xerox's Palo Alto (Calif.) Research Center and Ivan
was the co-creator of the structures project. "I was working
on special-purpose architecture for image processing at the time,"
recalls Conway. "I had become aware that there was a gap
between the sorts of systems we could visualize and what we could
actually get into hardware in a timely way.

For that reason, designers of digital systems were almost entirely
limited to using off-the-shelf logic. In one design, Conway recalls,
her group implemented an image-processing system in medium-scale
TTL ICs but couldn't make it sufficiently compact or cost-effective
without equivalent VLSI circuits. "At the same time I decided
to expand my knowledge from computer architecture to silicon,
I met Carver, who was coming upward from a knowledge of ICs into
computers," she says. The meeting point was an LSI systems
area that Conway and co-workers had formed at the Xerox research
center to simplify its design methods.

"We finished the draft of the book just before I had to
teach the prototype class at MIT in the fall of 1978," she
says. "We printed 300 copies at Xerox. Some were shipped
down to Carver, and I loaded the others into my station wagon
and drove off to MIT." The rest, as they say, is history.

The MIT class was a smash hit: the students learned about the
methodology in September, created their own designs in October
and November, and handed them in by early December. Six weeks
later, the masks for the multiproject chip design had been made
by electron-beam lithography at Micromask Inc. in Santa Clara,Calif.,
and the wafers had been processed at Hewlett-Packard Co.'s IC
processing lab in Palo Alto. The dice had been cut and packaged
with custom wiring running from the 40-pin dual in-line package
to the internal pads for each separate circuit project within
the chip. Each student received a silicon implementation of his
design. "Many of the designs were fully functional,"
Conway says.

Buoyed by the success of the project, she returned to California
in the spring of 1979 with an even more ambitious plan in mind:
a network of university projects modeled after hers at MIT. Each
would de-sign a multipro-ject chip, format it, and transmit it
to the Xerox research center via Arpanet, the packet-switched
communications network of the Department of Defense's Ad- vanced
Research Projects Agency.

"It was basically a stunt to show the power of the VLSI
design and implementation methods," states Conway. "It
involved broadcasting the rules of the game over Arpanet and creating
the VLSI implementation system software. We got Stanford, Berkeley,
Caltech, the University of Colorado, MIT, the University of Illinois,
the University of Washington, the University of Rochester, and
Carnegie-Mellon to participate." Again the chips were fabricated
at HP, but this time the cycle took only 29 days and the chips
were delivered on Jan. 2,1980.

Joint project.
This is one of the chips in the 1979 round-robin design project,
which Lynn Conway calls a network adventure involving students
in a multichip, multiuniversity project.

The MIT class marked a triumphant return there for Conway,
who had studied physics at the school before transferring to Columbia.
She had joined International Business Machines Corp. at its Yorktown
Heights, N. Y., research headquarters in 1964, moving to California
the next year when it established its advanced computer research
laboratory in Menlo Park. While at IBM, she made major contributions
to the architecture of ultrahigh-performance computing systems.
In 1969 she joined Memorex Corp., where she was processor architect
of a small business computer just before Memorex decided to get
out of that market. She joined the Xerox research center in its
early days in 1973 and began working on a combined optical character
recognizer - facsimile system. It was that project that triggered
her desire to create systems in VLSI.

Mead's interest in design automation goes back to the late
1960s, during a project to scale down ICs. "Calculations
on how small they could go showed that the answer was lots smaller
- down to 0.25 micrometer." Since at that time minimum feature
dimensions were down only to 10 micrometers, Mead's conclusion
itself was controversial. "But to this day the 0.25-micrometer
figure has held up, despite many people taking cracks at it,"
he says.

Nevertheless, posing the possibility that geometries that small
were within reach raised the central question of how to design
them. "Since then we've been trying to find out," Mead
says.

Along the road to that knowledge came Caltech's first algorithmic
software package for CAD. It evolved from a program for designing
printed circuit boards that Mead purchased in 1970 for $5,000
out of a special research and development fund. Mead's graduate
students designed an experimental clock chip, making their own
masks, which were run through Intel's fabrication line. "We
bootlegged it through unofficially," says Mead, "although
we told Robert Noyce [Intel's vice chairman] and Gordon Moore
about it later."

Any discussion about the Mead-Conway methodology comes back
to the book. "In electronics, a new wave comes through in
bits and pieces," observes Conway. "Usually, after it
has all evolved someone writes a book about it. What we decided
to do was to write about it while it is still happening.

"Our method was to project ourselves ahead 10 years, and
then write the book as though reflecting back upon a decade. Then
we would let the people in the community critique it, and let
the book itself become the focal point for the creation of methods."

With such a large body of interdisciplinary knowledge available,
Mead and Conway bad to struggle with selection. "We had to
figure out which knowledge was not needed," she says, "and
come up with the simplest subset required to do any digital design."
The pair decided that n-channel MOS was the ideal technology for
their methodology and also decided to bypass Boolean logic gates
as an intermediate step. Replacing them: simple fieldeffect transistor
switches and such devices as stacks, barrel shifters, and functional
blocks that are replicated to form larger subsystems. "We
also decided that we could normalize the design rule-to the resolution
of the process," says Conway. "Later on, we could ask
about the value of the minimum line width."

By putting together a set of design rules that was independent
of line width, Mead and Conway were avoiding some of the difficulties
of standard semiconductor design practice. They skirted the issues
of fine tuning of the fabrication line by making some fundamental
assumptions about such questions as how wide metal should be in
proportion to polysilicon. "We wanted to come up with something
that students would learn once and retain," says Conway,
"We chose the ratios based on Carver's knowledge of where
the processes are headed." These ideas anchored the book.

Any lingering doubts about the practicality of Mead and Conway's
approach must have been dispelled by the appearance of the Motorola
68000, the 16-bit microprocessor whose design was significantly
influenced by the duo's methodology. The 32-bit iAPX-432 from
Intel put the icing on the cake.

Besides the commercial-components that have benefited from
Mead-Conway design rules, a complex experimental floating-point
processor was designed by Digital Equipment Corp. using the duo's
principles. The job took much less time than with traditional
methods. Also notable among VLSI chips designed in academia is
MIT's public-key encoding IC with its 40,000 transistors.

For their work in structuring the methodology of the design
of very large scale, integrated circuits, summed up in the basic
textbook on the subject, "Introduction to VLSI Systems,"
Carver Mead and Lynn Conway have been designated by the editors
of Electronics as the recipients of the magazine's eighth Achievement
Award. The efforts of Mead, the Gordon and Betty E. Moore professor
of computer science and electrical engineering at the California
Institute of Technology at Pasadena, and Conway, research fellow
and manager of the VLSI system design area at Xerox Corp,'s Palo
Alto Research Center in California, have begun to transform the
thinking of semiconductor makers around the world.

Previous winners have been: in 1974, Gordon E. Moore, president
of Intel Corp. for his overall accomplishments; in 1975, the four
developers of integrated injection logic, Horst Berger and Siegfried
Wiedmann of International Business Machines Corp. and Arie Slob
and Cornelius Hart of Philips of the Netherlands; in 1976, Robert
C. Dobkin of National Semiconductor Corp. for linear-circuit development;
in 1977, Charles H. House of Hewlett-Packard Co. and B. J. Moore,
president of Biomation Corp., for major instrumentation innovations;
in 1978, Paul Richman, president of Standard Microsystems Corp.,
for advanced developments in MOS technology; in 1979, Andrew H.
Bobeck of Bell Laboratories for his role in the invention of magnetic-bubble
memories; and in 1980, Abe Offner, Jere D. Buckley, and David
A. Markle for their development of the projection mask aligner
at Perkin-Elmer Corp.